After the introduction of mass-produced personal computers such as the IBM PC in 1981 and the Apple Macintosh in 1984, the widespread use of clip art by consumers became possible through the invention of desktop publishing. For the IBM PC, the first library of professionally drawn clip art was provided with VCN ExecuVision, introduced in 1983. These images were used in business presentations, as well as for other types of presentations. It was the Apple Computer, with its GUI which provided desktop publishing with the tools required to make it a reality for consumers. The LaserWriter laser printer (introduced in late 1985), as well as software maker Aldus’ PageMaker in 1985, which helped to make professional quality desktop publishing a reality, with consumer desktop computers.
Dr. Porco further believes that Enceladus's orbit could have been much more eccentric in the past. The greater the eccentricity, the greater the tidal squeezing, and the resulting structural variations produce heat. In this case, the heat would have been saved inside the icy moon, melting some of the ice to replenish the liquid water sea. Dr. Porco continued to explain that "(T)he tidal flexing occurring now is not enough to account for all the heat presently coming out of Enceladus. One way out of this dilemma is to assume that some of the heat observed today was generated and stored internally in the past... (N)ow that the orbit's eccentricity has lessened, the heat emanating from the interior is a combination of heat produced today and in the past." Saturn, the smaller of the two gas-giant planets inhabiting our Solar System, is an enchanting world. It is dwarfed only by Jupiter, the larger gas-giant planet, and it is probably the most beautiful planet in our Solar System. Magical and mysterious, Saturn's lovely rings and tumbling moonlets of ice, evoke wonder in the eye of the beholder. Second, there is the issue of sharing wealth. The Third World wants to redistribute wealth in its favor, and it pursues this end by a combination of moral persuasion and threats of terrorism using weapons of mass destruction. A frontier could make such threats less persuasive. The Third World reaction to a space frontier initiative is unpredictable and possibly violent. This makes pioneering a taboo for Western governments. And that's why they would keep it secret.